Inverting Amplifier 反相放大器

inverting amplifier 反相放大器

V_in ---- R_in ----- V_mid ----- R_f ---- V_out

V_mid ----- -ve of op-amp

GND ----- +ve of op-amp


What's V_out?

Answer:

V_mid  = 0 for an ideal op-amp.

i = V_in / R_in = - V_out / R_f

=> V_out = - (R_f / R_in)V_in


What's the voltage gain?

Answer:

Gain = V_out / V_in = - (R_f / R_in)